In the field of medicine, conventional diagnosis systems for determining eye refraction are generally embodied as individual table top systems. In this case, for example, an autorefractor or an oscilloscope is used for objectively determining eye refraction. Besides the objective refraction determination by means of such apparatuses in which an objective measurement of the refraction of the eye is effected, so-called subjective refraction determinations are often carried out as well, in which different lenses or other optical elements having different optical properties are provided for a person (for example in an eyeglasses frame with a mount for such lenses) and the person indicates whether a visual impression improves or deteriorates. For this purpose, the person usually views an eye chart containing characters or symbols that is situated at a relatively large distance, for example 4 m.
Consequently, a relatively large amount of space is conventionally required for determining eye refraction. Moreover, devices necessary for this purpose are often relatively expensive. Therefore, it is desirable to provide more compact devices for determining eye refraction.
US 2013/0235346 A1 discloses using a smartphone or other computer units for eye examination, in particular for photorefraction. In this case, a camera of the smartphone is used to record one eye or both eyes of a person to be examined, and an illumination is provided for example via a flash or other lighting unit of the smartphone.
US 2012/0212598 A1 discloses illuminating an eye to be examined by means of a light emitting diode arrangement in order to be able to illuminate an eye from different directions. Thus, a specialized apparatus is again provided here which, under certain circumstances, is comparatively expensive.
DE 10153397 A1 discloses further methods and devices for measuring the refraction of an eye in which an eye is illuminated and then an image of the eye is evaluated.
US 2013/0027668 A1 discloses a method for subjective refraction determination, for which a mobile display device, in particular a smartphone, can be used. In this case, images are displayed which have to be made congruent by a subject.
DE 10 2008 012 268 A1 discloses a stationary device for objective refraction determination.
US 2006/0110008A1 discloses methods and devices for calibration-free eye gaze tracking.
DE 20 2011 103 183 U1 discloses an image separator which can be attached to a tablet computer for determining deficiencies in the visual acuity and refraction of an eye.